Microsoft is upgrading its new Outlook.com webmail service so that its users can communicate with Gmail users via instant messaging.

Microsoft says this new feature is 'one more reason to make the switch' from Gmail to Outlook.com

Microsoft is upgrading its new Outlook.com webmail service so that its users can communicate with Gmail users via instant messaging.

Outlook.com, which replaced Hotmail and offers a similar feature for chatting with people on Facebook and Skype, will roll out this Gmail capability over the next few days to its 400 million users worldwide, according to Microsoft.

People will also be able to engage in IM chats with Gmail users from the interface of their SkyDrive cloud storage and file sharing application.

"With this feature, the next time you're reading an email from someone who uses Gmail, you can reply with a quick chat right from your Outlook.com inbox. And if you're working together on an Office document in SkyDrive, you can send an instant message to a Google contact with just a click," wrote Microsoft official Douglas Pearce in a blog post Tuesday.

Pearce also took a dig at Gmail in the blog post, saying that the new feature is "one more reason to make the switch" and that part of the motivation was to help Outlook.com users chat "with friends stuck on Gmail."

Microsoft launched a preview of Outlook.com with much fanfare in July 2012, positioning it as a re-imagining of webmail from the data center to the user experience, and as a better option to Gmail and Yahoo Mail.

Microsoft has also been attacking Gmail for months via its Scroogled campaign, in which Microsoft accuses Google of disrespecting the privacy of Gmail users by matching ads to the text of their messages.

Earlier this month, Microsoft announced it had completed migrating all users from Hotmail to Outlook.com, whose improvements include a redesigned user interface, broad syncing capabilities, improved message sorting and native integration with Facebook, Twitter and other sites.